1. Field of the Invention
This invention relates to an electric double layer capacitor.
2. Related Background Art
In recent years, much attention has been paid to electric double layer capacitors (EDLC). This type of electric double layer capacitor has a pair of electrodes, and an electrolytic solution in contact with the pair of electrodes.
As an electrolytic solution, a nonaqueous electrolytic solution, wherein an electrolyte is dissolved in the organic solvent, is used.
A typical electrolytic solution is a solution of tetraethylammonium tetrafluoroborate (TEA+BF4−) as electrolyte, dissolved in propylene carbonate (PC) as organic solvent, or a solution of triethylmonomethylammonium tetrafluoroborate (TEMA+BF4−) dissolved in propylene carbonate.
Electrolytic solutions containing quartenary ammonium cations are also known (e.g., JP No. 2003-243260 and JP No. 2004-87956).